Boat propulsion mechanism with propellers in compartments



Jan. 15, 1957 I R. w. MILLER 2,777,414

BOAT PROPULSION MECHANISM WITH PROPELLERS IN COMPARTMENTS Filed June 15, 1955 I /4% f6 f0 :l I?" 7 w @J A a [9; a z; ,7; Z; 25 Z 1 L Z6 25 75/6 Z5 Z4 Z FIG. I."

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\ I l RUDOLPH W. MILLER United States Patent .BOAT PROPULSION MECHANISM WITH PRO- PELLERS IN COMPARTMENTS Rudolph W. Miller, Brooklyn, N. Y.

Application June 13, 1955, Serial No. 515,067

2 Claims. (Cl. 115-52) My invention relates to improvements in screw propellers for the propulsion of boats and, more particularly, to those which are housed within the vessel as distinguished from unshrouded propellers commonly keyed to the ends of driving shafts projecting rearwardly from the stern of the vessel. The principal object of my invention is to provide a more economical means for utilizing the power generated by the engine, or other source of energy used for propelling the boat, and for converting said energy into a propulsive force without substantial loss of power, than has hitherto been realized in boat propulsion so far as I am aware. Incidental to the main object is the provision of propeller shafts which are readily accessible both from within and outside the boat, for inspection, lubrication and repair.

The accompanying drawings of a boat which illustrate a practical embodiment of my invention show in Fig. 1 a vertical section indicated by the line 11 of Fig. 2, and in Fig. 2 a horizontal section indicated by the line 22 of Fig. 1.

The boat illustrated has two propellers 10, symmetrically disposed in the rear of the hull on opposite sides of a central vertical beam 11 and mounted for rotation in opposite directions in a single horizontal plane, the propeller 10 clockwise and the other propeller counterclockwise. Each propeller is housed in a separate compartment 12, 12, the top and bottom sides of which are formed by transverse water-tight partitions 13, 14 extending from one side of the boat to the other side, the inner end walls of both said compartments being supported, in part, by said beam 11 which is located half-way between the sides of the boat and extends through both said partitions to the bottom of the boat, while the outer ends of said compartments, which are flush with the respective sides of the boat, are open to the surrounding water, one at one side of the boat and the other at the other side. In each said compartment near the inner end thereof and held in position by the beam 11 and a surrounding bracing, generally indicated at 15, is a partial, arcuate casing 16, 16' for the propeller housed therein and which casing is open at both its ends 17, 17 and 18, 18. Except for a small portion at one end, each said casing has a contour conforming to the orbit described by the free ends of the blades of the corresponding propeller and a radius of curvature which leaves a very narrow clearance space between said casing and the free ends of said blades.

In operation, the propeller blades 27 strike the water at the side openings of the compartments 12, 12' and drive the entrained water rearwardly as indicated by the arrows in Fig. 2. Due to the presence of the casings 16, 16' and the fact that said casings are open at each of their ends and have a narrow clearance with the free ends of the blades, and also the fact that each of said compartments is open to the surrounding water at the respective sides of the boat, the water entrained by the blades will not penetrate to any substantial extent into ice the inter-blade areas marked A and B during the rotation of the propellers but will be driven rearwardly as indicated by the arrows in Fig. 2 and therefore will propel the boat without any substantial loss of the power generated by the engine. The propeller blades will always cut the water irrespective of their speed; and will develop a propulsive force proportional to their speed, whereas the unshrouded propellers of the prior art referred to above, if run at high speeds, create a centrifugal force which drives the water outward and away from the propellers so that at very high speeds the blades virtually operate in a partial vacuum and, as their speed further increases, cut the water very little, if at all. In other words, while my partially shrouded propellers operate to develop a propulsive force proportional to their speed, the relative efliciency of the unshrouded propellers gradually drops when run at high speed.

The propeller blades may be of the convential type adjustable to any desired pitch. The gear 20 is pinned to a main power shaft 35 and drives the gear 20' through two intermeshing idler gears 36, 36'. The propeller shafts pass through upper and lower compartments 23, 24 located above and below respectively the propeller compartments 12, 12'. In the said compartments 23, 24 are grease guns 25 of the piston type controlled by screws 26 for supplying lubrication to the propeller shafts. Manholes (not shown) may be provided in the horizontal partitions or decks 13, 14 to permit ready access to the compartments 23, 24 from inside the boat.

I claim as my invention:

1. In a boat having in the rear portion of its hull two Water-tight partitions extending from one side of the boat to the other side and a vertical beam supporting walls and extending through said partitions to the bottom of the boat half-way between the sides of the boat and which partitions and Walls together provide two separate compartments for housing respectively two propellers revolving in opposite directions in a single plane, the said transverse partitions forming the top and bottom sides of said compartments, the said walls forming the inner end sides of both said compartments, while at their outer ends, which are flush with the respective sides of the boat, said compartments are open to the surrounding water, one at one side of the boat and the other at the other side; the combination with each propeller of a partial arcuate casing therefor open at each end thereof and held in position by bracing it to said walls of said compartment in which that propeller is housed and near the inner end of said compartment, said partial casing having a contour conforming to the orbit described by the free ends of the blades of said propeller and a radius of curvature which leaves a very narrow clearance space between said casing and said blade ends.

2. The combination of claim 1 wherein the boat has a deck extending from one side to the other thereof and forming with one of the aforesaid partitions two additional compartments through which the respective shafts of said propellers extend, and means in said additional compartments for applying lubrication to said respective propeller shafts.

References Cited in the file of this patent UNITED STATES PATENTS 355,868 Fryer Jan. 11, 1887 415,611 Bucher Nov. 19, 1889 419,941 Hallett Jan. 21, 1890 2,378,589 Slack et al. June 19, 1945 FOREIGN PATENTS 21,848 Germany of 1883 

